1. Field of the Invention
An aspect of this disclosure relates to a developing device, a process unit, and an image forming apparatus.
2. Description of the Related Art
Japanese Laid-Open Patent Publication No. 2010-66769, for example, discloses an electrophotographic image forming apparatus including a toner amount detecting mechanism that detects the amount of remaining toner in a developing device or a process unit and reports to the user the timing to refill or replace the developing device or the process unit (this timing may be hereafter referred to as “toner replacement timing”).
The disclosed toner amount detecting mechanism includes a toner amount detecting part that changes its rotational positions according to the amount of remaining toner in a toner container of the developing device and an arm that is coupled with the toner amount detecting part and visible from the outside of the developing device or the process unit. When the amount of remaining toner in the toner container becomes less than or equal to a predetermined amount, the rotational range of the toner amount detecting part is extended toward a toner carrier of the developing device and the position of the arm is detected by a sensor provided at the image forming apparatus to detect a decrease in the amount of remaining toner (i.e., detect the toner replacement timing).
With the configuration disclosed in JP2010-66769, when toner is consumed in printing and the surface level of toner becomes lower than or equal to the height of the rotational shaft of the toner amount detecting part, or when the initial amount of toner is low and the surface level of toner is lower than or equal to the height of the rotational shaft of the toner amount detecting part, a space is formed between the toner amount detecting part and a limiting part (developing blade). In such a case, toner below the toner amount detecting part may be carried away due to a toner flow caused by the rotation of a toner supply part and a toner carrier. As a result, the rotational range of the toner amount detecting part is extended toward the toner carrier, the arm is detected by the sensor of the image forming apparatus, and the toner replacement timing is reported to the user even when a sufficient amount of toner for development still exists in the toner container.